Table of Contents
jbigtopnm - JBIG to PNM image file converter
jbigtopnm [ options
] [ input-file | - [ output-file ]]
Reads in a JBIG bi-level image entity (BIE) from a file or standard
input, decompresses it, and outputs a PBM or PGM file. If the input has
one plane, or you choose just one plane of it, the output is PBM. Otherwise,
the output is PGM.
JBIG is a highly effective lossless compression algorithm
for bi-level images (one bit per pixel), which is particularly suitable
for scanned document pages.
A JBIG encoded image can be stored in several
resolutions in one or several BIEs. All resolution layers except the lowest
one are stored efficiently as differences to the next lower resolution
layer. Options -x and -y can be used to stop the decompression at a specified
maximal output image size. The input file can consist of several concatenated
BIEs which contain different increasing resolution layers of the same image.
- -
- A single hyphen instead of an input file name will cause jbigtopnm
to read the data from standard input instead from a file.
- -x number
- Decode
only up to the largest resolution layer which is still not more than number
pixels wide. If no such resolution layer exists, then use the smallest one
available.
- -y number
- Decode only up to the largest resolution layer which
is still not more than number pixels high. If no such resolution layer exists,
then use the smallest one available. Options -x and -y can also be used together
in which case the largest layer that satisfies both limits will be selected.
- -b
- Use binary values instead of Gray code words in order to decode pixel
values from multiple bitplanes. This option has only an effect if the input
has more than one bitplane and you don't select just one of those bitplanes.
Note that the decoder has to be used in the same mode as the encoder and
cannot determine from the BIE, whether Gray or binary code words were used
by the encoder.
- -d
- Diagnose a BIE. With this option, jbigtopnm will only print
a summary of the header information found in the input file and then exit.
- -p number
- If the input contains multiple bitplanes, then extract only the
specified single plane as a PBM file. The first plane has number 0.
This
program implements the JBIG image coding algorithm as specified in ISO/IEC
11544:1993 and ITU-T T.82(1993).
The jbigtopnm is based on the JBIG
library by Markus Kuhn, part of his JBIG-KIT package. The jbgtopbm program
is part of the JBIG-KIT package. The most recent version of that library
and tools set is freely available on the Internet from anonymous ftp server
ftp.informatik.uni-erlangen.de in directory pub/doc/ISO/JBIG/.
jbigtopnm is
part of the Netpbm package of graphics tools.
pbm(5)
,pgm(5)
,pbmtojbg(1)
If you use jbigtopnm, you are using various patents, particularly
on its arithmetic encoding method, and in all probability you do not have
a license from the patent owners to do so.
Table of Contents